This invention relates to a method for removing acid gases from gaseous streams and, more particularly, to a process for removing CO.sub.2 and other acid gas constituents from the atmosphere by contacting the ambient air with an aqueous solution of 3-amino-1,2 propanediol of sufficient strength to purify it for rebreathing.
There is currently a great need for an improved method of regenerating breathing air, as well as other gas streams, from acid impurities. Such a method has several diverse applications, e.g., for air purification in submarines and other closed systems, scrubbing coke oven gases free of sulfur contaminants, and purification of feed-gas streams for many diverse utilities. The active solvent composition of the present invention is useful for removing acid gases, using methods already well known in the art.
A particular need of the Navy has been an improved absorber solution for removing CO.sub.2 from impure air in air purification systems. Currently, such systems are restricted by the use of monoethanolamine (MEA) as the regenerative CO.sub.2 absorbent. MEA solutions used for CO.sub.2 removal in submarine systems have several serious defects, such as (1) low regeneration efficiency, (2) evolution of ammonia, NH.sub.3, (3) high volatility, (4) toxicity and (5) lack of stability to oxidation under these operating conditions.
There have been several attempts at producing improved processes for the extraction of CO.sub.2 and other acid gases from gas streams. U.S. Pat. No. 3,632,519 deals with an earlier attempt to solve the problem of improved CO.sub.2 removal in submarine scrubber systems, and employs aminoalkyl alkylsulfones, not amino diols, as the regenerative cleaner. U.S. Pat. No. 3,502,428 employs a solution comprising several dialkanolamines together with a dioxo heterocyclic as the active purification agent. U.S. Pat. No. 3,387, 917 discloses the removal of CO.sub.2 using a composition comprising a solution of a 3-morpholinone compound and an alkanolamine. However, an amino diol has not been suggested as a basic element in any atmosphereregenerative cleaning process to date.